A row broke out tonight over the bidding for Gatwick airport as a Citigroup consortium was kicked out of the process.

Citi Infrastructure Investors declared the decision to eliminate it at an early stage was “bizarre in the extreme”.

Citi's team said: “To remove one bidder at this stage, therefore reducing the owner's position of leverage, is extraordinary and puzzling.”

It claimed that its bid, which was fully funded, would have allowed the airport to improve its passenger facilities.

BAA is selling Gatwick, Britain's second-biggest airport, for about £1.5 billion. The sale process was triggered by the Competition Commission ordering that BAA, which also owns Heathrow and Stansted, be broken up.

A source close to BAA's owner Banco Ferrovial said that the Citi consortium had been eliminated because it had bid too low and because the sellers were concerned about whether it could deliver on its bid.

Only two bidders remain in the race, sources said. They are Global Infrastructure Partners, which operates London's City Airport and a consortium which includes the owner of Manchester Airport.

The auction is being handled by HSBC and Royal Bank of Scotland.